<template>
  <!-- #ifdef H5 -->
  <th :class="{ 'table--border': border }" :colspan="colspan" :rowspan="rowspan"
      :style="{ width: width + 'px', 'text-align': align }" class="uni-table-th">
    <view :style="{ 'justify-content': contentAlign }" class="uni-table-th-content" @click="sort">
      <slot></slot>
      <view v-if="sortable" class="arrow-box">
        <text :class="{ active: ascending }" class="arrow up" @click.stop="ascendingFn"></text>
        <text :class="{ active: descending }" class="arrow down" @click.stop="descendingFn"></text>
      </view>
    </view>
  </th>
  <!-- #endif -->
  <!-- #ifndef H5 -->
  <view :class="{ 'table--border': border }" :style="{ width: width + 'px', 'text-align': align }" class="uni-table-th">
    <slot></slot>
  </view>
  <!-- #endif -->
</template>

<script>
/**
 * Th 表头
 * @description 表格内的表头单元格组件
 * @tutorial https://ext.dcloud.net.cn/plugin?id=3270
 * @property {Number}  width            单元格宽度
 * @property {Boolean}  sortable          是否启用排序
 * @property {Number}  align = [left|center|right]  单元格对齐方式
 * @value left    单元格文字左侧对齐
 * @value center  单元格文字居中
 * @value right    单元格文字右侧对齐
 * @event {Function} sort-change 排序触发事件
 */

export default {
  name: 'uniTh',
  options: {
    virtualHost: true
  },
  props: {
    width: {
      type: [String, Number],
      default: ''
    },
    align: {
      type: String,
      default: 'left'
    },
    rowspan: {
      type: [Number, String],
      default: 1
    },
    colspan: {
      type: [Number, String],
      default: 1
    },
    sortable: {
      type: Boolean,
      default: false
    }
  },
  data() {
    return {
      border: false,
      ascending: false,
      descending: false
    }
  },
  computed: {
    contentAlign() {
      let align = 'left'
      switch (this.align) {
        case 'left':
          align = 'flex-start'
          break
        case 'center':
          align = 'center'
          break
        case 'right':
          align = 'flex-end'
          break
      }
      return align
    }
  },
  created() {
    this.root = this.getTable('uniTable')
    this.rootTr = this.getTable('uniTr')
    this.rootTr.minWidthUpdate(this.width ? this.width : 140)
    this.border = this.root.border
    this.root.thChildren.push(this)
  },
  methods: {
    sort() {
      if (!this.sortable) return
      this.clearOther()
      if (!this.ascending && !this.descending) {
        this.ascending = true
        this.$emit('sort-change', {order: 'ascending'})
        return
      }
      if (this.ascending && !this.descending) {
        this.ascending = false
        this.descending = true
        this.$emit('sort-change', {order: 'descending'})
        return
      }

      if (!this.ascending && this.descending) {
        this.ascending = false
        this.descending = false
        this.$emit('sort-change', {order: null})
      }
    },
    ascendingFn() {
      this.clearOther()
      this.ascending = !this.ascending
      this.descending = false
      this.$emit('sort-change', {order: this.ascending ? 'ascending' : null})
    },
    descendingFn() {
      this.clearOther()
      this.descending = !this.descending
      this.ascending = false
      this.$emit('sort-change', {order: this.descending ? 'descending' : null})
    },
    clearOther() {
      this.root.thChildren.map(item => {
        if (item !== this) {
          item.ascending = false
          item.descending = false
        }
        return item
      })
    },
    /**
     * 获取父元素实例
     */
    getTable(name) {
      let parent = this.$parent
      let parentName = parent.$options.name
      while (parentName !== name) {
        parent = parent.$parent
        if (!parent) return false
        parentName = parent.$options.name
      }
      return parent
    }
  }
}
</script>

<style lang="scss">
$border-color: #ebeef5;

.uni-table-th {
  padding: 12px 10px;
  /* #ifndef APP-NVUE */
  display: table-cell;
  box-sizing: border-box;
  /* #endif */
  font-size: 14px;
  font-weight: bold;
  color: #909399;
  border-bottom: 1px $border-color solid;
}

.table--border {
  border-right: 1px $border-color solid;
}

.uni-table-th-content {
  display: flex;
  align-items: center;
}

.arrow-box {
}

.arrow {
  display: block;
  position: relative;
  width: 10px;
  height: 8px;
  // border: 1px red solid;
  left: 5px;
  overflow: hidden;
  cursor: pointer;
}

.down {
  top: 3px;

  ::after {
    content: '';
    width: 8px;
    height: 8px;
    position: absolute;
    left: 2px;
    top: -5px;
    transform: rotate(45deg);
    background-color: #ccc;
  }

  &.active {
    ::after {
      background-color: #007aff;
    }
  }
}

.up {
  ::after {
    content: '';
    width: 8px;
    height: 8px;
    position: absolute;
    left: 2px;
    top: 5px;
    transform: rotate(45deg);
    background-color: #ccc;
  }

  &.active {
    ::after {
      background-color: #007aff;
    }
  }
}
</style>
